TiO2[sbnd]Carbon composite using coconut waste as carbon source: Sonocatalysis and adsorption evaluation

Abstract

Activated carbon from coconut shells is known as an excellent adsorbent to remove contaminants, it was successfully inserted into the TiO2 structure via sol-gel method, and the sonocatalysis of methylene blue was evaluated. TiO2 nanoparticles and coconut shell were used for synthesizing activated carbon composite (TiO2COC) with carbon contents in the range of 0.5–10% by weight. These nanomaterials were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, Emission gun scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET) surface area, Fourier transform infrared spectroscopy (FT-IR), Field Emission Gun Scanning Electron Microscope (FEG–SEM) and Transmission electron microscopy (TEM). The physical-chemical properties of the catalysts were investigated in depth; in particular the kinetic studies conducted to determine the real degradation capacity of each material. The nanocomposites with carbon content of 0.5, 1.0, 2.0% in mass presented better catalytic activity when compared to a commercial one (Degussa-P25) and a lower dye adsorption was observed. The catalyst with 10% of carbon mass removed all methylene blue content through the adsorption process. Some catalysts reached high activity; the ultrasound effect was increased in 22% after only 2 h using low effective power output (40 W). The main reason for the increased catalytic was the perfect insertion of TiO2, which fill the coconut structure, sealing pores, reducing the carbon roughness and decreasing the TiO2 particle size. The electrical charge recombination on TiO2 surface enhances the sonocatalytic activity.